Grouped median and mode

For a grouped quantile, identify the class containing the required cumulative count. The grouped median estimate is L + [(N/2-C)/f]h, with lower boundary L, preceding cumulative count C, class frequency f and width h. The grouped mode estimate is L + [d1/(d1+d2)]h, where d1 = fm-fprevious and d2 = fm-fnext. These formulas interpolate; the resulting values need not be observed scores.